21. Hybrid additive manufacturing of Ti6Al4V with powder-bed fusion and direct-energy depositionSimon Malej, Matjaž Godec, Črtomir Donik, Matej Balažic, René Zettler, Thomas Lienert, Laurent Pambaguian, 2023, izvirni znanstveni članek Ključne besede: hybrid additive manufacturing, Ti6Al4V, tensile properties, defects, microstructure, phase transformation Objavljeno v DiRROS: 02.02.2024; Ogledov: 391; Prenosov: 184 Celotno besedilo (18,54 MB) Gradivo ima več datotek! Več... |
22. Effect of double-step and strain-assisted tempering on properties of medium-carbon steelPavel Salvetr, Andrea Školáková, Jakub Kotous, J. Drahokoupil, Daniel Melzer, Zdeňek Jansa, Črtomir Donik, Aleksandr Gokhman, Zbyšek Nový, 2023, izvirni znanstveni članek Ključne besede: medium-carbon steel, tempering, strengthening, mechanical properties, microstructure Objavljeno v DiRROS: 02.02.2024; Ogledov: 375; Prenosov: 163 Celotno besedilo (9,82 MB) Gradivo ima več datotek! Več... |
23. Effect of Cu alloying on mechanical properties of medium-c steel after long-time tempering at 500 °CPavel Salvetr, Aleksandr Gokhman, Milan Svoboda, Črtomir Donik, Ivana Podstranská, Jakub Kotous, Zbyšek Nový, 2023, izvirni znanstveni članek Ključne besede: long-time tempering, strengthening, Cu precipitate, medium-C steel, mechanical properties Objavljeno v DiRROS: 02.02.2024; Ogledov: 428; Prenosov: 171 Celotno besedilo (6,20 MB) Gradivo ima več datotek! Več... |
24. Complex interdependency of microstructure, mechanical properties, fatigue resistance, and residual stress of austenitic stainless steels AISI 304LPatricia Jovičević Klug, Matic Klug Jovičević, Michael Rohwerder, Matjaž Godec, Bojan Podgornik, 2023, izvirni znanstveni članek Ključne besede: stainless steel, AISI 304L, deep cryogenic treatment (DCT), microstructure, mechanical properties, fatigue, residual stress Objavljeno v DiRROS: 02.02.2024; Ogledov: 435; Prenosov: 185 Celotno besedilo (5,90 MB) Gradivo ima več datotek! Več... |
25. Effects of variated final temperature and workpiece thickness for hot rolling of aluminum alloy EN AW-8011Jakob Kraner, Peter Cvahte, Primož Šuštarič, Tomaž Šuštar, Črtomir Donik, Irena Paulin, Shae K. Kim, Kjung Il Kim, 2023, izvirni znanstveni članek Ključne besede: aluminum alloy, hot rolling, simulations, metallography, mechanical properties Objavljeno v DiRROS: 01.02.2024; Ogledov: 344; Prenosov: 178 Celotno besedilo (5,46 MB) Gradivo ima več datotek! Več... |
26. The influence of different fibres quantity on mechanical and microstructural properties of alkali-activated foamsKatja Traven, Mark Češnovar, Barbara Horvat, Vilma Ducman, 2022, objavljeni znanstveni prispevek na konferenci Povzetek: Alkali activated foams (AAFs) were produced using electric arc furnace steel slag (EAF) and ladle furnace basic slag (LS), obtained from two metallurgical companies in Slovenia. They were activated with a mixture of sodium water glass (Na2SiO3) and solid NaOH and foamed with hydrogen peroxide (H2O2). Pores were stabilized with the addition of Triton as a surfactant. Four types of fibres were added to the studied mixture (polypropylene (PP), polyvinyl-alcohol (PVA), basalt (B), and glass wool (GW)) in five different quantities: 0.5, 1.0, 1.25, 1.5 and 2.0 vol % in order to additionally stabilize the structure and thus improve its mechanical properties. The results of mechanical properties showed, that compressive strength was increased in all 20 specimens, partially due to the increased density as well as to the fibre addition. Flexural strength on the other hand was the most improved in the samples where PP and PVA fibres were added. The samples with the addition of B and GW fibres on the other hand showed only small or no improvement in flexural strength in comparison to the referenced sample. Additionally, the microstructure of used fibres and selected foams was also investigated by the means of SEM analysis. Ključne besede: fibers, alkali activated foams, properties Objavljeno v DiRROS: 31.01.2024; Ogledov: 323; Prenosov: 167 Celotno besedilo (4,05 MB) Gradivo ima več datotek! Več... |
27. The development and assessment of alkali activated paving blocksAna Frankovič, Vilma Ducman, Lubica Kriskova, Efthymios Tatsis, Petrica Petrica, Yiannis Pontikes, 2022, objavljeni znanstveni prispevek na konferenci Povzetek: In recent years great attention has been placed by the building sector on alkali-activated technology based on metakaolin, fly ash and ground granulated blast furnace slag (GGBFS), but also on emerging precursors such as by-products from non-ferrous metallurgy. The present work focuses on the development of alkali-activated binders from two slags, one from primary and one from secondary copper production, which were finely milled, blended with GGBFS, and activated with K-based alkali silicate solution with a 1.7 SiO2/K2O molar ratio. The aggregate to paste mass ratio was 2. The mixtures were cast, and cured for a designated time at room temperature and 60% RH. The so-obtained paving blocks were then tested in accordance with European standard for concrete paving blocks. The following properties were measured: splitting tensile strength, abrasion resistance, slip and skid resistance, resistance to freeze-thaw and resistance to freeze-thaw in the presence of de-icing salts. Their properties were compared to those of commercially available concrete paving blocks, and it was found that the performance of the alkali-activated pavers was generally comparable with the concrete pavers, while certain properties (e.g., abrasion resistance, freeze-thaw resistance and freeze-thaw resistance in presence of de-icing salts) were considerably better. Ključne besede: slags, alkali activated pavers, properties Objavljeno v DiRROS: 21.12.2023; Ogledov: 334; Prenosov: 204 Celotno besedilo (4,29 MB) Gradivo ima več datotek! Več... |
28. Antibacterial effect of polymethyl methacrylate resin base containing TiO2 nanoparticlesAnamarija Zore, Anže Abram, Aleksander Učakar, Ivo Godina, Franc Rojko, Roman Štukelj, Andrijana Sever Škapin, Rajko Vidrih, Olivera Dolić, Valentina Veselinović, Klemen Bohinc, 2022, izvirni znanstveni članek Povzetek: Restorations in dentistry must reproduce the aspect of the patient’s natural teeth and require non-toxicity, biocompatibility, and good mechanical properties in order to last longer. Restorations are permanently in contact with microbes that can adhere to and form biofilms. The purpose of this study was to determine the adhesion extent of Streptococcus mutans to polymethyl methacrylate (PMMA) resin base containing TiO2 nanoparticles. To understand the adhesion of Streptococcus mutans on the modified resin-based surfaces, the following surface properties were measured: the roughness, contact angle, zeta potential and CIE color parameters. Evaluation of tensile stress performance in TiO2 modified PMMA showed that the maximum tensile stress of the modified PMMA resin decreases with an increasing amount of TiO2 nanoparticles. The increasing amount of TiO2 decreases the roughness and causes contact angles in the border between hydrophilic and hydrophobic surfaces. All the studied surfaces are negatively charged and added TiO2 tends to increase the zeta potential. The addition of TiO2 nanoparticles increases the lightness and decreases the intensity of the red and yellow color. The increasing addition of TiO2 nanoparticles into PMMA increases the morphological change of bacterial cells. Ključne besede: bacterial adhesion, Streptococcus mutans, polymethyl methacrylate resin, TiO2, surface properties Objavljeno v DiRROS: 20.12.2023; Ogledov: 357; Prenosov: 191 Celotno besedilo (14,32 MB) Gradivo ima več datotek! Več... |
29. Polypropylene blends with m-EPR copolymers : mechanical and rheological propertiesIztok Švab, Anđela Pustak, Matjaž Denac, Andrijana Sever Škapin, Mirela Leskovac, Vojko Musil, Ivan Šmit, 2018, izvirni znanstveni članek Povzetek: The effects of two metallocene ethylene-propylene-based elastomers (m-EPR1 and m-EPR2) differing in molecular mass and viscosity on mechanical, rheological and interfacial properties were compared. The m-EPR elastomers were added to iPP in 2.5, 5, 10, 15, and 20 vol.%. Torque values, elongation at break and impact strength measured of the iPP/m-EPR1 blends were higher than the iPP/m-EPR2 blends due to higher molten viscosity of m-EPR1 than m-EPR2 copolymer. Slight differences in Young moduli as well as in tensile strength at yield and at break might indicate that tensile properties of iPP/m-EPR blends were not significantly affected by difference in viscosity or molecular mass, miscibility and spherulite size. Optimization diagrams indicated the metallocene m-EPR copolymers are efficient impact modifiers for polypropylene and showed good balancing of mechanical properties in iPP/m-EPR blends. Ključne besede: isotactic polypropylene, metallocene ethylene-propylene-based elastomers, blend, mechanical properties, adhesion parameters Objavljeno v DiRROS: 13.12.2023; Ogledov: 425; Prenosov: 196 Celotno besedilo (3,19 MB) Gradivo ima več datotek! Več... |
30. Particle size manipulation as an influential parameter in the development of mechanical properties in electric arc furnace slag-based AAMKatja Traven, Mark Češnovar, Vilma Ducman, 2019, izvirni znanstveni članek Povzetek: Alkali-activated materials (AAM) have gained recognition as a promising alternative to technical ceramic and building materials owing to the lower energy demands for production and the potential to use slag as a precursor. In the present study, five sets of slag-based AAM pastes were prepared with different particle sizes (fractions d < 63, 63 < d < 90, and 90 < d < 125 μm in different mass ratios) under the same curing regime and using a fixed precursor to activator (water) mass ratio. Precursors and the hardened AAM are evaluated using BET, XRD, XRF, SEM, FTIR, reactivity of precursors by leaching, and mercury intrusion porosimetry (MIP). Chemical analysis indicated only marginal differences among the different-sized fractions of input materials, whereas the BET surface area and reactivity among the precursors differed significantly-smaller particles had the largest surface area, and thus, higher reactivity. The mineralogical differences between the precursors and hardened AAM were negligible. The results revealed that compressive strength was significantly influenced by particle size, i.e., a threefold increase in strength when the particle size was halved. Microstructural evaluation using MIP confirmed that the porosity was the lowest in AAM with the smallest particle size. The low porosity and high reactivity of the fine fractions led to the highest compressive strength, confirming that manipulation of particle size can significantly influence the mechanical properties. Ključne besede: alkalijsko aktivirani materiali, žlindra iz obločne peči, mehanska aktivacija, mehanske lastnosti, poroznost, alkali-activated materials (AAM), electric arc furnace steel slag, mechanical activation, mechanical properties, porosity Objavljeno v DiRROS: 22.11.2023; Ogledov: 522; Prenosov: 224 Celotno besedilo (2,26 MB) Gradivo ima več datotek! Več... |